Hey guys, new user to this forum and am needing advice on Grad ND filters. Here's my equipment that I'll use filters with/on:

D80016-35VR24-120/4.0VR

-- I know the square Cokin filter system is popular, and I never considered using them until now. I always use traditional, if you will, threaded filters. However, I've never used Grad ND or any ND filter and don't want to blindly buy $400 worth of filters if I'm not going to get the most benefit. Obviously both lenses above are 77mm....what I "possibly" plan on buying in the future is the Zeiss 21mm (82mm filter thread) once I get acclimated to Nikon SLRs. Just got rid of my Canon 5d2 and 17-40L about a month ago -- and still learning differences in Canon vs. Nikon ergonomics.

What's most "flexible" system? I see that an adaptor is required based on lens -- to match filter holder, correct? I don't want to lock in a fortune on filters if they'll vignette on a larger filter thread. I also would like to experiment with ND filters (not just Graduated) for various scenes. I shoot landscapes about 90% of time and most of you know how a southern California sun will wash out a scene!! Please post a link to product if you have the time. It would mean a lot to me.

Right now I'm just using Nikon NC filters on my glass....and I do see another forum topic on polarizers. For that filter, I plan on getting just a "traditional" threaded filter. Thanks guys!

The Lee Foundation Kit is a great way to go for adding filters. It uses 100mm (4") filters so you don't have to worry about vignetting with most lenses. The filter holder attaches to your lens with a threaded adapter so all you need for lenses with different filter sizes is a new adapter ring. Filters available from Lee come in either resin or glass and they offer a wide variety of filter types, including both grad ND and traditional ND.